非点源污染中多溴联苯醚的土－气交换研究

The environmental pollution and human health risk of the polybrominated diphenyl ethers (PBDEs) has become the focus of global attention. The environmental behavior of PBDEs between soil and air has a direct impact on the long distance transportation, fate and human exposure of them, and needs systematically and further study. In this study, we choose the non-point source pollution urban area as the research region. The soil-air volatilization, particle size distribution, gas-particle distribution, and transportation from air to soil of PBDEs will be investigated to explore the process and mechanism of PBDEs soil-air exchange. We simulate the actual environment in laboratory and use the isotope labeling method to study the soil-air volatilization of PBDEs, then analyze the characteristics of PBDEs in the air and soil from the study area, and apply the fugacity model to identify the direction of soil-air exchange. The pollution characteristics of PBDEs in different particle size particles will be analyzed to identify the particle size distribution of PBDEs. The absorption model and adsorption model of gas-particle will be used to clarify the mechanism of PBDEs gas-particle distribution. Then the air-soil transportation and deposition flux of PBDEs with dry and wet deposition will be studied. This study is helpful for us to understand the pollution characteristics and environmental behavior of PBDEs in non-point source pollution area, and will provide the basic theoretical support for the study of PBDEs' transportation, transformation, fate and human exposure risk.

多溴联苯醚(PBDEs)的环境污染及人体健康风险已成为全球关注的热点，PBDEs在土壤和大气间的交换直接影响着其长距离迁移、归趋及人体暴露，因此该过程需要系统深入地研究。本项目以非点源污染的城市地区为研究区域，从PBDEs的土气挥发、粒径分布与气粒分配、气土迁移三个方面对PBDEs的土—气交换过程和机制进行研究：以实验室模拟实际环境，同位素标记法研究PBDEs的土气挥发，结合实测的研究区域大气与土壤中PBDEs污染特征以及逸度模型分析土气交换方向；分析大气不同粒径颗粒物PBDEs污染特征，解析PBDEs粒径分布，以气—粒吸收模型和吸附模型拟合阐明PBDEs气粒分配机制；结合干湿沉降中PBDEs污染特征和环境因素揭示PBDEs随干湿沉降的气土迁移规律及沉降通量。本研究有助于系统了解非点源污染地区PBDEs的污染特征和环境行为，为研究PBDEs的迁移转化、归趋和人体暴露风险提供基础理论支撑。

作为典型持久性有机污染物，多溴联苯醚(PBDEs)和多氯联苯（PCBs）在土壤和大气间的交换直接影响着其长距离迁移、归趋及人体暴露。本研究以北京市作为研究区域，通过实际环境采样、PBDEs和PCBs定性定量分析、模型拟合、实验室模拟和同位素标记等方法，从粒径分布与气粒分配、气土迁移、土气挥发等方面对PBDEs和PCBs在大气和土壤中的污染特征和交换进行了研究。研究结果如下：北京市大气中Σ8PBDEs浓度为2.36－22.67pg·m-³，污染水平较低，PBDEs在气相中的含量稍高于颗粒相，在细颗粒中更易富集，大气中PBDEs的气粒分配未达到平衡状态；北京市土壤中Σ8PBDEs浓度为1.21－4088.25pg·g-1dw，总体呈现城市>郊区>农村的趋势；PBDEs的大气湿沉降通量高于干沉降通量，且城区的PBDEs沉降通量高于郊区；通过逸度模型分析得出城区和郊区PBDEs是从大气向土壤的净沉降，农村地区PBDEs处于土－气交换较平衡状态；同位素标记PBDEs土－气挥发实验显示不同PBDEs单体的挥发量和挥发速率不同，BDE-209由土壤向大气的传输能力较弱。北京市大气中Σ28PCBs浓度为44－402pg·m-³，PCBs在气相中的含量高于颗粒相，在细粒子尤其是粒径≤0.49μm的粒子中更易富集，大气中PCBs的气粒分配未达到平衡状态；北京市土壤中Σ28PCBs浓度为50.52－10306.18 pg·g-1dw，总体呈现城市>郊区>农村的趋势；PCBs的大气湿沉降通量高于干沉降通量；通过逸度模型分析得出城区和郊区PCBs处于土－气交换较平衡状态，农村地区PCBs是从土壤向大气的净挥发，土壤是PCBs的二次来源。本研究结果有助于系统了解非点源污染地区PBDEs和PCBs的污染特征和环境行为，为PBDEs和PCBs的迁移转化、来源、归趋和人体健康风险研究提供基础理论支撑。